Straight hole bit



Jan. 9, 1940. J. D. HUGHES STRAIGHT HOLE BIT Filed April 22, 1938 Patented Jan. 9, I

S AT-Es"; PATENT OFFICE .mfill'ffit w A corporation oi Texas Application April 22, 1938, Serial No. 203,472

The invention relates'to 'a bit used in the rotary'inethod of drilling wells and particularly to a bit which is adapted to drill a straight hole.

In the rotary method of drilling wells the bit is attached to. thelcwer end of. a'drill stem and penetrates the formation by rotary motion usually in a clockwise direction. A portion of the weight oi the string of drill pipe is allowed to rest upon the drill bit to force it into the forma- 1 tion, and of course, flushing fluid is circulated through the drill stem and the bit to wash the cuttings away from the cutter blades.

In view of the fact that the bit rotates constantly in one direction it usually has a tendency to form the wellbore in a spiral as it moves downwardly into the formation. In other instances the bit may engage a fissure in a rocky formation or boulders or other more or less rigid obstructions in the softer formations which tend to deflect the wellbore from a substantially vertical path.

Various types of equipment have been provided forv correcting the deflection of the well bore, such as whipstocks which have an inclined facevv to change the inclination of the bore, and.

other types of equipment. The present invention directs itself to a particular type of bit wherein a plurality of cutter blades are provided in such a construction and arrangement that a greater unit area pressure will be .created'against one portion of the side wall of the well bore, so that there is a tendency to direct the well bore along a curve in the direction of the side wall against which the greater pressure is exerted.

It is one of the objects of the invention to pro vide a drill bit having one blade which extends radially a greater distance than the remaining blades.

Another object of the invention is to provide m a drill bit which will cause the drill stem to move eccentrically in the well bore.

Still another object of the invention is to pro- I vide a method of correcting the inclination of the well bores by applying .the transverse component of force caused by raising a portionoi the drill stern away froin the low side of the well bore against the side wall-on the low side, so as, to cut away the-side .wall and gradually curve the well here from its inc'lination into a vertical to direction.-

Another object of the invention is to provide a method of drilling straight holes'by cutting away the side wall on'the low side'of thewell bore.

Still another object ofthe invention is to pro- 66 vide a three-way drag hit one blade of which carries a plurality of outstanding cutter teeth on the side wall, which teeth project a greater distance than the side wall of the remaining blades.

Still another object of the invention is to provide a drill bit which will maintain a straight 5 hole by correcting the inclination automatically due to the construction of the bit used.

Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawing wherein:

Fig. 1 is a side elevation of a drill bit embodying the invention.

Fig. 2 is a bottom plan view of the bit of Fig. i.

Fig. 8 is a transverse sectional view taken on 1 the line 3-3 of Fig. 1; and looking downward.

Fig. 4 is a diagrammatic view showing the general arrangement of the method of correcting the inclination of a well bore and showing the bit in position and applying the excess pressure 20 against the low side of the hole.

The bit which may be used in practicing the invention is illustrated at 2 in Fig. l and includes a body portion 8 having a shank l, which is threaded for connection to a drill sub or collar 25 8, which is best seen in Fig. 4. The drill stem 6 is connected to the drill collar 5 and extends to the surface. Flushing liquid may be circulated through the passage 1 in the drill stem and is arranged to discharge from the ports 8 in the 80 bottom of the body 3. A chamber in in the body 3 feeds the flushing fluid to all three of the openillustrated, three blades l4, l5 and 16', which are symmetrically arranged to extend radially from the body. A discharge port 8 is directly in front of each of the blades. In addition to the lower; cutting edge ii on each blade there is a side wall cutter or reamer portion ii on the blades i4 and I5, which two blades are identical in their construction.

The third blade I6 is of particular or peculiar construction, first, because it extends inwardly to a point l8 across the center of the body. In

' this manner this heel portion l8 of the blade I6 will cut away the central portion of the formation being penetrated.

- The blade I! has another peculiarity in that it extends radially agreater distance from the body than do the blades II and it. This is apparent from both Figs. 2 and 3. The side wall of the blade I is formed with a plurality of teeth or lugs II, which are spaced apart by the recesses or notches 22. The lower notch 23 of the group may be of less depth than the remaining notches, if desired. The side walls i1 and III may be rearwardly inclined as seen in Figs. 2 and 3.

It is intended that hard surfacing material such as tungsten carbide or other suitable substances will be applied to the faces ii and to the side wall portions I1 and 2| particularly upon the teeth 2|.

In ordinary drilling operations the side walls I! of the blades tend to ream the hole and maintain it of a proper gauge, which is the sire of the bit, but with the present type of bit it is intended that the blade I 8 will accomplish a greater reaming action on one side of the hole than it does on the. other when the hole is inclined away from the vertical and this excessive reaming action will occur on the side wall of the hole, which is on the low side.

This action will be accomplished by applying a greater unit area pressure against the side wall due to the fact that this blade I projects radially from the body a greater distance than the other blades and due also to the fact that the teeth II are provided and'the pressure against the side wall will in this manner be concentrated upon these teeth portions so that they will penetrate the side wall more than will the reaming edges on the other blades. This is particularly true when the well bore is inclined but when the well bore is vertical the action of the blade I will be uniform in its reaming action all the wayaround the side wall.

For purposes of illustration 'a three-way bit has been shown but it is to be understood that any desired number of blades may be provided so long as one blade isof the type of the blade II. I More than one blade may be constructed like the blade I! if desired.

The operation of the method is best seen in Fig. 4 where the well bore has been drilled and for some reason or other has deviated from the vertical and is inclined. As shown the side wall II is on the low side of the hole whereas the side wall on the high side of the hole is indicated at 32. been connected to the drill collar I which may be of any desired length and is usually of a heavy rigid construction. In some instances such drill collars may be It to ill feet in length and of a very thick gauge of material, so that the rigidity thereof will tend to hold the bit against sharp deflections or inclinations away from the verti cal. In the figure the drill collar has been shown as broken between its ends.

Above the drill collar 5 is a drill-stem Band by connecting successive lengths of drill stem to each other the bit 2 has been lowered into the well bore and in Fig. 4 is shown as having been seated upon the bottom 33 of the well bore 30. The bit has'been illustrated in such a position that the blade I8 is shown as pressing against the side wall 3| on the low side of the hole and it should be particularly noted that the collar 5 and the drill stem i are not centered in the well bore 30 but that they have been raised away from the low side wall 3| to a position near the The drill bit 2 is shown as having 7 side wall 32, and that this raising of the drill collar and drill stem away from the low side was cause:I by the blades i0 pressing against the side wal If the well bore is vertical there would be a transverse or horizontal component of force but it would be uniform against the side wall throughout its circumference because rotation of the bit would cause the drill stem and drill collar to move eccentrically in the well bore, but the eccentricity would be uniform and the blade I would accomplish a uniform reaming action throughout thecirc'umference of the well bore. When, however, the well becomes inclined as seen in Fig. 4, it seems obvious that the reaming action will be increased on the lower portion of the side wall, as at 3|, due to the fact that the drill collar and drill stem are inclined from the vertical and every time the eccentric blade i6 comes around to the low side of the hole the reaming action will be increased. This increase begins on a diameter perpendicular to the sheet of the drawing and increases gradually until it reaches a diameter in the plane of the sheet of drawing and then decreases again as it approaches the-perpendicular diameter again. Of course, when the other blades II and i5 travel around on the low side of the hole they permit the drill collar and drill stem to settle down toward the low side of the hole 3| and the pressure on the reaming edges ,II is reduced but every time the blade It comes around to the low side of the hole a greater unit area pressure to accomplish a reaming action occurs, first, because the drill stem and drill collar must be lifted away from the low side of the hole if the resistance of the formation to cutting is sufiicient.

If the formation is very soft, of course, .the blade it will merely cut it away and the weight of the drill stem-and drill collar will thence be utilized to accomplish a reaming action tending to correct the inclination of the hole. On the other hand, if the formation resists cutting the resistance will be overcome by a force which is increased due to the fact that the drill collar and drill stem will have to be lifted somewhat and the transverse component of this force, due to the weight of the drill collar and drill stem. will be available to increase the force tending to cut away the low side of the hole.

As the bit is rotated the well bore will be reamed away on the low side II, as seen in Fig. 4, so that the path of the well bore will be curved so that the side wall 3| gradually approaches the vertical as at 35.

The provision of the lugs 2| and notches 12- facilitates the cutting action on the low side of the hole when the well bore is inclined.

One of the particular advantages of the present bit is the fact that the inclination of the well bore is corrected automatically, as seen in Fig. 4, but when the well bore approaches the vertical the transverse component tending to force the blade it against the low side of the hole is reduced, because the drill collar and drill stem reside in the wellat a lesser inclination so that the rate of correction is decreased as the vertical is approached, and is increased when the inclination is the greatest.

When the well bore becomes vertical then the reaming action becomes uniform all the way around the circumference of the wellbore and the drilling of the bore continues in a vertical position. If for some reason the bit is again de flected the blade I6 immediately proceeds to ream away the low side of the hole at a rate in proportion to the inclination whichhas occurred so that the bit automatically compensates ior any inclination which may occur, and the driller may proceed with his drilling operation at a uniform rate without withdrawing the drill stem, to survey the well bore hole, to introduce a whipstock, or other deflecting tool. The driller is assuming that his well bore will remain substantially vertical because the bit automatically compensates for any inclination which occurs and this compensation is directly in proportion to the amount of inclination. When the inclination disappears and the well bore becomes vertical then the reamingaction is uniform and no further correction will occur.

Broadly the invention contemplates a means and method of drilling well bores whereby the bore will be maintained in a vertical position and any inclination which occurs will be automatically corrected only to the extent that the well bore. again becomes vertical.

What is claimed is:

1. A drag bit of the character described for correcting and maintaining the direction of a well bore, including a body and blades, transverse cutting edges in substantially the same horizontal plane on all of said blades, and a serrated cutting side wall on one of said blades, said last blade extending radially farther than the other blades.

2. A straight hole bit including a body, blades thereon, one of said blades extending radially a greater distance than the remaining blades to create a greater unit area pressure on the low transverse plane so that said bit body moves ecblade having alternate notches and teeth on the side wall, and bottomcutting edges on all of said blades which edges are in substantially the, same transverse plane so as to cut the bottom of the more as the side teeth out the low side walloi the bore.

4. A drag bit for correcting the inclination of and drilling straight bores comprising a body, a plurality of radial blades on the body and projecting below the body, transv'ersebottom cutting edges on all the blades disposed at the same elevation so that all blades cut the bottom of the bore being drilled, one of said blades including a portion extending radially a greater distance than the remaining blades -to cut the lower side wall when the bore is inclined.

5.,A drag bit for correcting the inclination of and drilling straight bores comprising a body, a plurality of radial blades on the body and projecting below the body, transverse bottom cutting edges on all the blades disposed at the same elevation so that all blades cut the bottom of the bore being drilled, one of said blades including a portion extendingradially agreater distance than the remaining blades to cut the lowerside wall when the bore is inclined, and aninner portion on the same blade extending across the longitudinal axis of the body. a

' 7 JAMES D. HUGHES. 

